Transmitting device for transmitting a digital information signal alternately in encoded form and non-encoded form

ABSTRACT

A transmitter transmits a digital information signal via a transmission medium. The digital information signal can be divided into one or more sub-signals. Each sub-signal is transmitted as a non-encoded or as an encoded signal. Thus, the sub-signal is transmitted depending on the compression that can be achieved by the encoder. If the compression is low the sub-signal is transmitted in non-encoded form. For the receiver, an identification is added to the composite signal to be transmitted. A first component of the identification signal indicates if one or more sub-signals are transmitted in encoded form. A second component of the identification signal indicates for each sub-signal, whether it appears in encoded or non-encoded form in the composite signal. The invention provides a composite signal with a minimal number of bits.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention is related to the field of signal encoding for compressingthe signal and subsequent decoding to reproduce the signal.

2. Related Art

The invention relates to a transmitting device for transmitting adigital information signal via a transmission medium, including:

an input for receiving the digital information signal,

an encoder for encoding the digital information signal and generating anoutput signal.

The invention further relates to a receiver for receiving a compositesignal via a transmission medium, to a method of transmitting a digitalinformation signal via a transmission medium, and to a record carriercarrying a digital information signal having portions which have been orhave not been encoded by a given encoding method.

A transmitter and receiver of the type defined in the opening paragraphsis known from the AES preprint 4563 “Improved Lossless Coding of 1-BitAudio Signals” by Fons Bruekers et al, 103rd AES Convention (New York,US). The known transmitter is intended for efficiently reducing the bitrate for the transmission of a digital information signal. A compositesignal thus obtained includes an encoded version of the digitalinformation signal. On an average, the composite signal obtained by theknown transmitter contains less bits than a composite signal in whichthe digital information signal has not been encoded.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a transmitter and/orreceiver which transmits a digital information signal with a smaller orat the most equal number of bits. The invention also enables moreinformation to be stored on a record carrier.

To this end, a transmitter in accordance with the invention, furtherincludes:

a controller for generating a control signal to be applied to theencoder, and the encoder generates portions of the output signal in theform of encoded portions of the digital information signal under theinfluence of a control signal of a first type, and generates portions ofthe output signal in the form of portions of the digital informationsignal under the influence of a control signal of a second type;

a first identification signaler for generating a first identificationsignal of a first type which indicates that the output signal possiblyincludes a portion of the digital information signal which has beenencoded in the encoder, and a first identification signal of a secondtype which indicates that the output signal does not include anyportions of the digital information signal which have been encoded bythe encoder;

a second identification signaler for generating, for a portion of thedigital information signal, a second identification signal of a firsttype depending on the control signal of the first type and the firstidentification signal of the first type, and a second identificationsignal of a second type depending on the control signal of the secondtype and the first identification signal of the first type;

a combiner for combining the output signal of the encoder, the firstidentification signal and, if the first identification signal is of thefirst type, the second identification signal so as to obtain a compositesignal to be applied to the transmission medium.

In a receiver in accordance with the invention, a demultiplexer derivesa first identification signal of a first type and a second type from thecomposite signal, and decodes a signal portion into a portion of thedigital information signal and supplies the portion of the digitalinformation signal depending on a control signal of a first type andsupplies signal portion as a portion of the digital information signalin a substantially unmodified form depending on a control signal of asecond type, and the receiver further includes:

a controller for generating the control signal for application to thedecoder, which controller generates a control signal of the first typedepending on the first identification signal of the first type.

A method in accordance with the invention includes the steps of:

generating a control signal;

generating portions of an output signal in the form of encoded portionsof the digital information signal under the influence of a controlsignal of a first type;

generating portions of the output signal in the form of portions of thedigital information signal under the influence of a control signal of asecond type;

generating a first identification signal of a first type which indicatesthat the output signal possibly includes a portion of the digitalinformation signal which has been encoded in the encoder, or a firstidentification signal of a second type which indicates that the outputsignal does not include any portions of the digital information signalwhich have been encoded by the encoder;

generating a second identification signal of a first type depending onthe control signal of the first type and a first identification signalof the first type;

generating a second identification signal of a second type depending onthe control signal of the second type and the first identificationsignal of the first type;

combining the output signal of the encoder, the first identificationsignal and, if the first identification signal is of the first type, thesecond identification signal so as to obtain a composite signal; and

applying the composite signal to the transmission medium.

A record carrier in accordance with the invention carries a digitalinformation signal having portions which have not been encoded and otherportions which have been encoded by using a given encoding method, andcarries a first identification signal which is of a first type whichindicates that the record carrier may carry a portion of the digitalinformation signal encoded using the given encoding method.

The invention is based on recognition of the fact that by using anencoder, the number of bits required to transmit a digital informationsignal is not always reduced. In the encoder, some signals give rise toan output signal which requires more bits for the representation of thedigital information signal than the digital information signal itself.In the device and the method in accordance with the invention, in orderto preclude this increase, the representation having the smaller numberof bits is transmitted together with an identification signal, whichindicates whether or not the signal has been encoded by a given encodingmethod. A record carrier can store a maximum number of bits. If therecord carrier is obtained using the method in accordance with theinvention, it can store a composite signal with a larger digitalinformation signal.

BRIEF DESCRIPTION OF THE DRAWING

These and other aspects of the invention will be described in moredetail with reference to FIGS. 1 to 8.

FIG. 1 is a block diagram of a first embodiment of a transmitting devicein accordance with the invention.

FIG. 2 is a block diagram of an embodiment of a receiver in accordancewith the invention.

FIG. 3 is a block diagram of a transmitter in the form of a recordingapparatus.

FIG. 4 is a block diagram of a receiver in the form of a reproducingapparatus.

FIG. 5 shows a structure of a Volume Space on a record carrier.

FIG. 6 shows a structure of an audio Area on a record carrier.

FIG. 7 shows a layout of an Audio Sector on a record carrier.

FIG. 8 shows the relationship between Multiplexed Frames and AudioSectors.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is a block diagram of a first embodiment of a transmitter inaccordance with the invention. The transmitter has an input terminal 2for receiving a digital information signal such as a digital audiosignal. The digital audio signal may have been obtained by converting ananalog version of the digital audio signal into the digital informationsignal in an analog-to-digital (A/D) converter. The digital informationsignal may take the form of 1-bit signals, such as a bitstream. It isalso possible that the digital information signal received via the inputterminal has been obtained using a plurality of pre-processingoperations, not shown. The pre-processing operations may include, forexample, an encoding method. The digital information signal may includeone or a plurality of signal portions. One signal portion of the digitalinformation signal can, for example, be the information recorded in onetrack on the record carrier, or a group including a number of samples ofthe digital information signal. The signal portions together constitutethe digital information signal. A digital information signal is, forexample, all the audio information recorded on a record carrier or amusic item which is transmitted via a transmission medium. The inputterminal 2 is coupled to an input 4 of encoding unit 6. The encodingunit 6 includes an encoder 7 to convert the signal received at the input4 into an encoded signal. The encoder 7 may be a lossless encoder asdescribed in the AES preprint 4563 “Improved Lossless Coding of 1-BitAudio Signals” by Fons Bruekers et al., 103rd AES Convention (New York,US). Alternatively, the encoder 7 may be a lossy encoder. The encodingunit 6 supplies an output signal to an output 10. Depending upon acontrol signal applied to a control input 8, a switching element 9couples an output of the encoder 7 or the input 4 to the output 10, as aresult of which, the output signal includes the encoded signal or thesignal received at the input 4.

The encoding unit 6 may also include an encoder 7 which supplies thedigital information signal to the output of the encoder in a modified orunmodified form depending on the coefficients used in the encoder. Forexample, in the Application EP 98200869 (PHN 16.831), not yet publishedat the time of filing of the present Application, an arithmetic encoderis described, which in the case of a coefficient having the value 0.5,applies the signal received at the input of the arithmetic encoder tothe output of the arithmetic encoder in a substantially unmodified form.By the selection of suitable coefficients in the encoder depending onthe control signal, the encoder can apply an encoded digital informationsignal or a substantially unmodified digital information signal to theoutput. In the case of coefficient controlled encoding, the encodingunit 6 does not include a switching element as shown in FIG. 1.

The embodiment shown in FIG. 1 also has a controller 12 for applying thecontrol signal to the control input 8 of the encoding unit 6 and to acontrol input 16 of the identification signaler 18 for deriving anidentification signal. The controller 12 may take the form of an inputterminal. However, the controller 12 may alternatively include reductionestimator 12 a to determine the data reduction which is achieved or canbe achieved by the conversion of the signal into the encoded signal inthe encoder 7. For example, if an entropy encoder is used in the encoder7, it is possible to determine with satisfactory probability the degreeof data reduction of the signal caused by encoding with the aid of thestatistical distribution of a signal applied to the input of the entropyencoder and/or the probability table used by the entropy encoder. When aprior estimate is made, it is not necessary to wait until the signal hasbeen encoded in order to determine the data reduction. As a result, adigital information signal can be processed and transmitted more rapidlyby the transmitter. Reduction estimator 12 a can determine the datareduction of both the digital information signal and the individualsignal portions. Subsequently, the data reduction is compared with apredetermined factor. If encoding leads to a data reduction greater thana predetermined factor, a control signal of the first type is generated.If encoding leads to a data reduction smaller than the predeterminedfactor, a control signal of the second type is generated.

Identification signaler 18 derives an identification signal depending onthe control signal received at the control input 16. The identificationsignal is applied to an output 20. Identification signaler 18 alsoindicates, in the identification signal, whether the encoding unit 6supplies a signal to the output 10 of the encoding unit 6 in an encodedform or in a substantially unmodified form. The identification signalincludes a first component that indicates that possibly a signal portionof the digital information signal is supplied to the output 10 of theencoding unit 6 in an encoded form. If the identification signalincludes this first component, the identification signal also includes asecond component, which indicates for each of the signal portions,whether the signal is supplied to the output 10 of the encoding unit 6in an encoded form or substantially unmodified.

The combiner 22 has a first input 24 coupled to the output 10 of theencoding unit 6, a second input 26 coupled to the output 20 of theidentification signaler 18 for generating the identification signal, andan output 28. The combiner generates a composite signal from the outputsignal of the encoding unit 6 and the identification signal. Thecomposite signal is applied to the output 28 in order to be transmittedvia a transmission medium (TRM).

The transmitting device as described hereinbefore operates as follows.The digital information signal is applied to the input terminal 2 and issupplied to the encoding unit 6. The controller 12 applies a controlsignal to the encoding unit 6. If the control signal of the first typeis received, the output signal of the encoding means contains theencoded signal. If the control signal of the second type is received,the switching element 9 couples the input 4 of the encoding unit 6 tothe output 10 of the encoding unit 6. The output signal of the encodingunit 6 then contains the digital information signal. The control signalcan be defined externally. For example, for some types of digitalinformation signals, encoding these digital information signals wouldlead to an increased number of bits. In such case, the digitalinformation signal would be expanded rather than compressed. This isundesirable, because this expansion may give rise to problems. Theseproblems may be, for example, an inadequate storage capacity or aninsufficient bandwidth in order to transmit the digital informationsignal via the transmission medium. A control signal of the second typeis applied when it is known that encoding of the digital informationsignal does not yield the desired data reduction. In that case, thedigital information signal is not applied to the combiner 22 in anencoded form. However, when it is known that encoding leads to asignificant data reduction, then a control signal of the first type willbe applied. The identification signaler 18 generates the identificationsignal corresponding to the relevant control signal. The combiner 22combines the output signal of the encoding unit 6 and the identificationsignal to form a composite signal. Subsequently, the composite signal istransmitted via the transmission medium. By selecting that version ofthe digital information signal having the smaller number of bits in thecomposite signal, the transmitting device will make optimum use of thestorage capacity on a record carrier or will make optimum use of thebandwidth of a transmission medium.

In the preceding paragraph it has been described how a digitalinformation signal is transmitted using the transmitter in accordancewith the invention. The digital information signal is then regarded asone signal. However, the digital information signal may include aplurality of signal portions. A signal portion may be one music item,but may, alternatively, be a group of consecutive samples of the digitalinformation signal. The transmitter in accordance with the invention,also enables each individual signal portion to be transmitted coded ornot coded using the encoder 7 or a switching element 9. The transmitterthen includes an identification signaler 18 which, for the whole digitalinformation signal and/or each individual signal portion, determineswhich manner (i.e., encoded or not encoded) requires the least number ofbits for transmitting the digital information signal via thetransmission medium. For some of the signal portions, encoding will leadto data reduction. For other signal portions, encoding will lead to adata increase. The control signal will then alternately be of the firsttype or the second type, respectively, in such a manner that, the signalportions for which the data reduction provided by the encoder 7 isunsatisfactory do not appear in encoded form in the output signal of theencoding unit 6, and the other signal portions do appear in encoded formin the output signal. The identification signal now includes a firstcomponent which indicates that, possibly, one signal portion appears inencoded form in the composite signal. Moreover, there is a secondcomponent, which, for each of the portions, specifies whether the signalportion appears in an encoded form or not, in this encoded form in thecomposite signal.

FIG. 2 shows an embodiment of a receiver in accordance with theinvention, for receiving a composite signal TRM. A version of thedigital information signal is derived from the composite signal TRM. Anexact or a non-exact copy of the digital information signal will bederived depending on the coding used in the transmitter. The compositesignal TRM is received at the input 60 of demultiplexer 62. Thedemultiplexer 62 derives an output signal and an identification signalfrom the composite signal TRM. The output signal contains a version ofthe digital information signal, and is applied to an output 64. Theversion of the digital information signal may include one or more signalportions of the digital information signal. A signal portion can be atrack of a disc or a group of consecutive samples of the digitalinformation signal. The identification signal, which specifies how theversion of the digital information signal has been encoded, is suppliedto an output 66. The identification signal specifies for each signalportion whether or not it has been encoded.

Identifier 70 has an input 68 coupled to the output 66 of thedemultiplexer 62. Identifier 70 derives a control signal from theidentification signal, which control signal is to be transferred to acontrol output 72. A control signal of a first type is derived from theidentification signal when the corresponding portion of the outputsignal at the output 66 of the demultiplexer 62 has been encoded by theencoder. A control signal of a second type is derived from theidentification signal, when the corresponding portion of the outputsignal at the output 66 of the demultiplexer 62 has not been encoded bythe encoder.

The decoding unit 76 has an input 74 coupled to the output 64 of thedemultiplexer 62. A control input 78 is coupled to the control output 72of the identifier 70. The decoding unit 76 includes a decoder 77 todecode the signal received at the input 74 into a decoded signal, andincludes switching element 79. Depending on the control signal appliedto the control input 78, the switch 79 couples an output of the decoder77 or the input 74 to the output 80. As a result, the output signal ofthe decoding unit 76 includes a decoded version of the signal receivedat the input 74, or the output signal is just the signal received at theinput 74. If the transmitter uses a lossless coding, the signal appliedto the output 80 will be an exact copy of the digital information signalapplied to the input of the transmitter. The decoder can be a lossydecoder or a lossless decoder. An example of a lossless decoder isdescribed in the AES preprint 4563 “Improved Lossless Coding of 1-BitAudio Signals” by Fons Bruekers et al., 103rd AES Convention (New York,US). The decoded signal is applied to the output 80 in response to acontrol signal of the first type. The signal is received at the input 74is applied to the output 80 in substantially unmodified form, inresponse to a control signal of the second type. A signal may include asignal component of the digital information signal, or the entiredigital information signal. The decoding unit 76 has its output 80coupled to the output terminal 82.

The receiver shown in FIG. 2 operates as follows. In the demultiplexer62 a version of the digital information signal and an identificationsignal are derived from the composite signal TRM. The identifier derivesa control signal from the identification signal. The identificationsignal has a first component which indicates whether one or severalportions of the version of the digital information signal appear in theversion encoded in a given manner. If the first component is notpresent, the version of the digital information signal is the version ofthe digital information signal which has not been encoded in the givenmanner. The first component can be recorded in a Table of Content, TrackList or Block Header of, for example, a record carrier in the form of anoptical disc. If the first component is present, the identificationsignal includes a second component. The second component specifies howthe corresponding signal portion appears in encoded form in the versionof the digital information signal. The control signal is generateddepending on the first and the second component. The control signaldetermines whether or not the signal applied to the input 74 must bedecoded before it is applied to the output 80.

FIG. 3 shows a transmitter in the form of a recording apparatus forrecording the digital information signal on a record carrier. Thecircuit block 300 in FIG. 3 is equivalent to the block diagram of FIG.1. The output 28 of the circuit block 300 corresponds to the output 28of the combiner 22 in FIG. 1. The recording apparatus further includesan error correction encoder 302, a channel encoder 304, and a writer 306for writing the signal onto the record carrier 308. Error correctionencoders and channel encoders are generally known from the related art.The record carrier 308 can be of the magnetic type. In the present case,the writer 306 includes one or several magnetic heads 310 to record theinformation in a track on the record carrier 308. In another embodiment,the record carrier 308 is an optical information carrier 308′. In thiscase, the writer 306 includes an optical recording head 310 forrecording the information in a track on the record carrier 308′.

FIG. 4 shows a reproducing receiver for reproducing the digitalinformation signal on the record carrier. The circuit block 400 in FIG.4 is equivalent to the block diagram of FIG. 2. The input 60 of thecircuit block 400 corresponds to the input 60 of the demultiplexer 62 inFIG. 2. The reproducing receiver further includes a reader 402, achannel decoder 406 and an error detector 408 for detecting or, ifpossible, an error corrector 408 for correcting errors in the signal.Channel decoders and error detectors/correctors are generally known fromthe related art. The reader 402 reads the signal recorded on the recordcarrier 402 b and supplies the signal thus read to a channel decoder406. The record carrier 402 b can be of the magnetic type. In thepresent case, the reader 402 includes one or several magnetic read heads402 a for reading the information from a track on the record carrier 402b. In another embodiment, the record carrier 402 b is an opticalinformation carrier 402 b′. In this case, the reader 402 includes anoptical read head 402 a for reading the information from a track on therecord carrier 402 b′.

A transmitter and a receiver, in accordance with the invention, oftenprocess the signals in a byte-oriented fashion. The first component ofthe identification signal can be recorded in, for example, the Table ofContent, Track List or Block Headers. The second component of theidentification signal can be recorded at the beginning of each signalportion in the composite signal, for example, at the beginning of eachframe. A frame includes a part of the digital information signal and theparameters intended for the receiving device. As a result of thebyte-oriented processing, it is desirable that each frame begins at aboundary of a byte or a plurality of bytes. When a signal portionappears in the composite signal in an encoded form, this portion in thecomposite signal may start with parameters which specify how thesubsequent group of bits in the signal should be decoded. In the presentcase, the bits are processed separately and, consequently, the secondcomponent may include only one bit for this signal portion. The numberof bits of an encoded signal need not correspond to an integral numberof bytes. In order to ensure that the next portion of the compositesignal begins at a byte boundary, it may be necessary to insert a numberof bits at the end of the encoded signal in the composite signal. When asignal portion appears in the composite signal in a non-encoded form,i.e. in the original form, the second component may require one bit orone byte of space per signal portion, depending on the signal processingthat is used. In the case that a byte-oriented signal processing isused, and a signal portion includes an integral number of bytes, thesecond component preferably occupies one byte of space. As a result, theboundaries of portions of the composite signal remain at the byteboundaries.

FIG. 5 shows a structure of the volume space on a record carrier inaccordance with the invention. The volume space on the record carrierhas been divided into: a File System Area, Master TOC Area, 2-ChannelStereo Area, Multi Channel Area, and Extra Data Area. The 2-ChannelStereo Area and the Multi Channel Area are referred to as Audio Areas.Each record carrier should have the Master TOC Area and at least oneAudio Area. The record carrier may optionally have a File System Area.In this case, the File System Area includes a file system in accordancewith the ISO 9660, File and Directory Naming Standard, and/or the UnitData File (UDF) specification. ISO 9660 specifies the volume and filestructure of record carriers in the form of a CD-ROM. The Extra DataArea may optionally be used for storing audio-related information. Ifthe record carrier has an Extra Data Area, the record carrier shouldhave a UDF and/or an ISO 9660 file. The data in the Extra Data Area canbe addressed via the file system. The file system is stored in the FileSystem Area. If the File System Area is not large enough to store thefile system, the remainder of the file system can be stored in the ExtraData Area.

The Master TOC Area includes three identical copies of the Master TOC.The Master TOC describes the record carrier at the highest level. Thethree copies of the Master TOC are situated at the same location on eachrecord carrier and have a fixed size of 10 sectors. A sector has a sizeof 2048 bytes. The first sector includes general information about therecord carrier, such as the size and the location of the Audio Areas onthe record carrier, album information, catalog number, type of recordcarrier, and the date of the record carrier.

FIG. 6 shows a structure of an Audio Area on the record carrier. TheAudio Area includes a Track Area having Audio Tracks containing audioinformation, and an Area TOC with control information. All 2-channelstereo Audio Tracks are arranged in the 2-channel stereo Area. All MultiChannel Tracks are arranged in the Multi channel Area. Each Audio Areaincludes an Area TOC-1, a Track Area with Audio tracks, and an AreaTOC-2. The content of the Area TOC-1 and of the Area TOC-2 is identicaland includes a copy of the Area TOC. The location of the Area TOC-1 andthe Area TOC-2 of each Audio Area is defined in the Master TOC.

The information stored in a Track Area is a Byte Stream. A Byte Streamis stored in an integral number of sectors. A sector used by a ByteStream is called an Audio Sector. A Byte Stream is divided intoMultiplexed Frames having a duration of {fraction (1/75)} second. A ByteStream includes an integral number of Multiplexed Frames and is thesuccession of all Multiplexed Frames in an Audio Area. FIG. 7 shows alayout of an Audio Sector. An Audio Sector includes a fixed number ofbytes, for example, 2048 bytes. Each Audio Sector begins with an AudioHeader and is followed by at least one Packet. If the last byte of aPacket in an Audio Sector does not lie within the last byte of an AudioSector, Stuffing or Padding bytes are added up to the last byte of anAudio Sector. A Packet can contain only one of the following data types,namely Audio Data, Supplementary Data, or Padding Data. A Packet ofAudio Data is called an Audio Packet. A Packet of Supplementary Data iscalled a Supplementary Packet. A Packet of Padding Data is called aPadding Packet. A packet can belong to only one Audio Sector. An AudioSector should include at least one packet. An Audio Sector includes amaximum of seven Packets.

A Multiplexed Frame includes an integral number of Packets. AMultiplexed Frame should include at least one Audio Packet. In addition,a Multiplexed Frame may include Supplementary Data Packets and PaddingPackets. An Audio Frame includes the concatenated Audio Packets in aMultiplexed Frame. A Supplementary Data Frame includes the concatenatedSupplementary Data Packets in a Multiplexed Frame. A Padding Frameincludes the concatenated Padding Packets in a Multiplexed Frame. AudioFrames, Supplementary Data Frames and Padding Frames are referred to asElementary Frames.

Each Multiplexed Frame has a time code expressed in minutes, seconds,and the sequence number of the frame in the second. The first AudioFrame in the Track Area of an Audio Area has the time code 0. The timecode is incremented in each subsequent Multiplexed Frame in the entireTrack Area.

FIG. 8 shows the relationship between Multiplexed Frames and AudioSectors. The Audio Frames are shown at the top. The Audio Frames can beof different lengths when the Audio Frames have been obtained bylossless coding. These Audio Frames are divided into Audio Packets. InFIG. 8, the Audio Frames N are divided into four Packets (N,0), (N,1),(N,2) and (N,3). The Audio Packets are subsequently arranged in theAudio Sectors. As stated hereinbefore, each Audio Sector begins with anAudio Header, followed by at least one Packet. In FIG. 8, theSupplementary Data Packets are referenced S, the Padding packets arereferenced p, and the Audio Headers are referenced h. Thus, in FIG. 8,the Audio Sector M+3 includes an Audio Header, Audio Packet (N,3),Supplementary Data Packet N, Audio Packet (N+1,0), Supplementary DataPacket N+1, Padding Frame N+1 and Audio Frame (N+2,0).

The Area TOC includes control information for the Track Area of theAudio Area belonging to the Area TOC. Control information can, forexample, include: the Byte_Rate of the Multiplexed data in the AudioArea expressed as the number of bytes per second, the sample rate usedfor the Audio Area, and the frame format. The frame format defines theframe structure of the multiplexed audio signal in the Track Area.Possible types of frame formats are, for example, Multi Channel flexibleFormat plain DSD, Fixed format 2-channel stereo plain DSD 3 frames in 14sectors, Fixed format 2-channel stereo plain DSD 3 frames in 16 sectors,or Lossless encoded flexible format. In the case that the frame formatindicates that the frame structure has the Lossless encoded flexibleformat, then at least one frame in the Track Area may have been Losslessencoded.

An Audio Sector begins with an Audio Header and is followed by at leastone Packet. The Audio Header includes information about the AudioSector, such as the number of Packets in the Audio Sector, the number ofAudio Frames which begin in the Audio Sector, and a parameter whichindicates whether the Audio Area to which the Audio Sector belongs hasor does not have a frame format of the Lossless encoded flexible type.This parameter has been included in order to preclude some errors whichcan occur during reproduction of the Audio signals. The Audio Sector isthe smallest unit that can be read from the information carrier. Whenthe data on the record carrier is read using the file system, then theAudio Sectors can be read directly, and it is not necessary to firstread the Area TOC belonging to the Audio Area in which the Audio sectorlies. This makes it possible, to first, read an Audio Sector having aframe structure of the type Fixed format 2-channel stereo plain DSD 3frames in 14 sectors. The audio signals are then of the DSD type. DSDsignals are 1-bit signals and can be applied directly to the output ofthe receiving device. If after reading of the aforementioned AudioSector, an Audio Sector is read which has a frame structure of theLossless encoded flexible format type, the audio signals in this audiosector can be lossless encoded. If the lossless encoded signal isapplied to the output, the applied signal may damage loudspeakerscoupled to the receiving device. Therefore, during the read-out of eachAudio Sector, the receiving device must be capable of detecting whetherthe read-out data has been or has not been lossless encoded so as toenable the data thus read to be processed correctly.

In addition to information about the Audio Sector, the Audio Header alsoincludes information about each Packet in the Audio Sector andinformation about each frame that begins in the Audio Sector.Information about an Audio Packet can be, for example, an indicationwhether the Packet is the first Packet of a Frame, the type of data inthe Packet, and the length of the Packet. The length can be represented,for example, as the number of bytes in the Packet. A Packet can containonly one data type, for example Audio Data, Supplementary Data, orPadding Data. For each frame that begins in the Audio Sector, the AudioHeader contains frame information. Thus, each frame contains a timecode. If the frame format is of the Lossless encoded flexible formattype, the Audio Header of each frame which starts in the sectorspecifies the number of audio channels used, for example, 2, 5 or 6channels, and the number of audio sectors (N_sectors) over which thestarting frame has been divided. If, for example, the first Packet of aFrame starts somewhere in sector X and the last packet is situated inAudio Sector Y, N_sectors is equal to Y−X+1. Before a receiving devicecan decode the Lossless encoded data, it should first read all thepackets belonging to a Frame. For this purpose, the informationN-sectors is relevant.

An Audio Stream also includes the DSD audio signal in lossless encodedor non-lossless encoded form. An Audio Stream is the concatenation ofall the Audio Frames in a Byte Stream. A Lossless encoded Audio Framehas a variable length. An Audio Frame, in an Audio Area for which theArea TOC specifies that the frame format is of the Lossless encodedflexible format type, starts with a bit that indicates whether the AudioData appears in the Audio Frame in lossless encoded or non-losslessencoded form. Thus, it is possible that the Area TOC indicates, that theframe format is of the Lossless encoded flexible format type, and thatall Audio Frames contain the Audio Data in non-lossless encoded form.

An apparatus in accordance with the invention may include both atransmitting device and a receiving device. The combination of theapparatuses shown in FIG. 4 and FIG. 5 yields an apparatus using adigital information signal can be recorded on the record carrier, andthe recorded digital information signal can be read form the recordcarrier and can be reproduced at a later instant. Another possibility,is that two apparatuses, which both include a transmitting and receivingdevice, communicate with one another via one or several transmissionmedia. Using its transmitting device, the first apparatus transmits adigital information signal to the second apparatus via a firsttransmission medium. The second apparatus receives this signal using thereceiving device and transfers it to the output. In a similar manner thesecond apparatus can transmit a digital information signal to the secondapparatus via a second transmission medium. Depending on the physicalimplementation of the transmission medium use will be made of one ormore transmission media.

What is claimed is:
 1. A transmitter comprising: input means forreceiving a digital information signal; means for encoding the digitalinformation signal and generating an output signal including: portionsof the output signal in the form of encoded portions of the digitalinformation signal under the influence of a control signal of a firsttype, and portions of the output signal in the form of portions of thedigital information signal under the influence of a control signal of asecond type; control means for generating the control signal of thefirst type and the control signal of the second type; means forgenerating: a first identification signal of a first type whichindicates that the output signal possibly includes a portion of thedigital information signal which has been encoded in the encoding means;and a first identification signal of a second type which indicates thatthe output signal does not include any portions of the digitalinformation signal which have been encoded by the encoding means; meansfor generating, for a portion of the digital information signal: asecond identification signal of a first type depending on the controlsignal of the first type and the first identification signal of thefirst type; and a second identification signal of a second typedepending on the control signal of the second type and the firstidentification signal of the first type; combining means for combiningthe output signal of the encoding means, the first identification signaland, if the first identification signal is of the first type, the secondidentification signal, so as to obtain a composite signal to be appliedto a transmission medium.
 2. The transmitter of claim 1, furthercomprising means for determining whether encoding of a portion of thedigital information signal leads to a data reduction by at least apredetermined factor, and for generating the control signal of the firsttype if encoding of the portion of the digital information signal leadsto a data reduction larger than the predetermined factor.
 3. Thetransmitter of claim 1, further comprising: at least one of errorcorrection means for error encoding of the composite signal into anerror-encoded signal and channel encoding means for channel encoding ofthe composite signal into a channel-encoded signal; and recording meansfor recording at least one of the error-encoded signal and thechannel-encoded signal on a record carrier.
 4. The transmitter of claim1, further comprising: means for determining whether encoding of aportion of the digital information signal leads to a data reduction byat least a predetermined factor, for generating the control signal ofthe first type if encoding of the portion of the digital informationsignal leads to a data reduction larger than the predetermined factor;at least one of error correction means for error encoding of thecomposite signal into an error encoded signal and channel encoding meansfor channel encoding of the composite signal into a channel-encodedsignal; and recording means for recording at least one of theerror-encoded signal and the channel-encoded signal on a record carrier.5. A method comprising the steps of: receiving a digital informationsignal; encoding the digital information signal, depending on acomposite control signal, to produce an output signal; generating thecomposite control signal, including a first control signal of a firsttype and a second control signal of a second type; generating portionsof the output signal in the form of encoded portions of the digitalinformation signal under the influence of said first control signal;generating portions of the output signal in the form of portions of thedigital information signal under the influence of said second controlsignal; generating: a first identification signal of a first type whichindicates that the output signal possibly includes a portion of thedigital information signal which has been encoded; or a firstidentification signal of a second type which indicates that the outputsignal does not include any portions of the digital information signalwhich have been encoded; generating a second identification signal of afirst type depending on the first control signal and the a firstidentification signal of the first type; generating a secondidentification signal of a second type depending on the second controlsignal and the first identification signal of the first type; combiningthe output signal, the first identification signal and, if the firstidentification signal is of the first type, the second identificationsignal so as to obtain a composite signal; applying the composite signalto a transmission medium.
 6. The method claim 5, further comprising thesteps of: producing at least one of an error correction encoded signalof the composite signal and a channel encoded signal of the compositesignal; and applying at least one of the error correction encoded signaland the channel encoded signal to the transmission medium.
 7. The methodof claim 5, in which the transmission medium is a record carrier.
 8. Arecord carrier obtained by the method of claim 7, in which the recordcarrier is an optical or magnetic recording medium.
 9. The method ofclaim 5, further comprising the steps of: producing at least one of anerror correction encoded signal of the composite signal and a channelencoded signal of the composite signal; and applying at least one of theerror correction encoded signal and the channel encoded signal to thetransmission medium; and providing a transmission medium which is arecord carrier.
 10. A transmitter/receiver apparatus, for transmitting adigital information signal via a transmission medium, comprising: arecord carrier; a digital information signal embodied on said recordcarrier, said digital information signal having portions which have beenor have not been encoded using an encoding method; and a firstidentification signal of a first type, wherein said first identificationsignal indicates that the digital information signal has been encodedusing the encoding method.
 11. The record carrier of claim 10, furthercomprising a second identification signal for each portion of thedigital information signal; and in which: a second identification signalof a first type indicates for a portion of the digital informationsignal, that this portion has been encoded by means of the givenencoding method; and a second identification signal of a second typeindicates for a portion of the digital information signal, that thisportion has not been encoded by means of the given encoding method. 12.The record carrier of claim 10 in which: the record carrier furthercomprises a disc carrying digital information including at least onedata area, each data area including a table of contents and a track areadivided into frames each including a portion of a representation of thedigital information signal; the table of contents contains a firstidentification signal of a first or a second type, said firstidentification signal of said second type indicating that each frame inthe track area contains a portion of the digital information signalwhich has not been encoded using the given encoding method, and saidfirst identification signal of said first type indicating that a framein the track area possibly contains a portion of the digital informationsignal which has been encoded using the given encoding method; and if adata area contains said first identification signal of said first type,each frame includes a second identification signal which indicateswhether the frame contains a portion of the digital information signalwhich has been or has not been encoded by means of the given encodingmethod.
 13. The record carrier of claim 10, in which: the record carrierfurther comprises a second identification signal for each portion of thedigital information signal; a second identification signal of a firsttype indicates for a portion of the digital information signal, thatthis portion has been encoded by means of the given encoding method; anda second identification signal of a second type indicates for a portionof the digital information signal, that this portion has not beenencoded by means of the given encoding method; the record carrierfurther comprises a disc carrying digital information including at leastone data area, each data area comprising a table of contents and a trackarea divided into frames each including a portion of a representation ofthe digital information signal; the table of contents contains a firstidentification signal of a first or a second type, said firstidentification signal of said second type indicating that each frame inthe track area contains a portion of the digital information signalwhich has not been encoded using the given encoding method, and saidfirst identification signal of said first type indicating that a framein the track area possibly contains a portion of the digital informationsignal which has been encoded using the given encoding method; and if adata area contains said first identification signal of said first type,each frame includes a second identification signal which indicateswhether the frame contains a portion of the digital information signalwhich has been or has not been encoded by means of the given encodingmethod.
 14. A receiver comprising: receiving means for receiving acomposite signal from a transmission medium; demultiplexing means forderiving at least one signal portion from the composite signal and forderiving a first identification signal of a first type and a second typefrom the composite signal; decoding means for decoding at least onesignal portion and for decoding a signal portion into a portion of thedigital information signal and to supply the portion of a digitalinformation signal depending on a control signal of a first type and tosupply a signal portion as a portion of the digital information signalin a substantially unmodified form depending on a control signal of asecond type; and means for generating the control signal for applicationto the decoding means including a control signal of the first typedepending on the first identification signal of the first type.
 15. Thereceiver of claim 14, in which: the demultiplexing derive a firstidentification signal of a second type from the composite signal; andthe means for generating the control signal generate a control signal ofthe second type depending on the first identification signal of thesecond type.
 16. The receiver of claim 14, in which: the demultiplexingmeans derive, depending on the identification signal of the first type,a second identification signal associated with each individual signalportion; and the means for generating the control signal generate acontrol signal of the first type depending on the second identificationsignal of the first type and generate a control signal of the secondtype depending on the second identification signal of the second type.17. A receiving device as claimed in claim 14, in which the receiverfurther comprises: a device for reading out a signal recorded on arecord carrier; and at least one of channel decoding means for thechannel decoding of the read-out signal and error detection/correctionmeans detecting and correcting errors in the read-out signal.
 18. Thereceiver of claim 14, in which: the demultiplexing means derive a firstidentification signal of a second type from the composite signal; themeans for generating the control signal generate a control signal of thesecond type depending on the first identification signal of the secondtype; the demultiplexing means derive, depending on the identificationsignal of the first type, a second identification signal associated witheach individual signal portion; the means for generating the controlsignal generate a control signal of the first type depending on thesecond identification signal of the first type, and generate a controlsignal of the second type depending on the second identification signalof the second type; and the receiver further comprises: a device forreading out a signal recorded on a record carrier; and at least one ofchannel decoding means for the channel decoding of the read out signaland error detection/correction means for detecting and correcting errorsin the read-out signal.